Have you ever been behind a car with a driver that has one foot on the brakes and the other on the gas. It seems to resemble the effect you are looking for and incredibly distracting and annoying. When brake lights go on you expect them to be making a stop or rapid deceleration so you do the same as well as the people behind you and all of the sudden you are speeding up, slowing down, back and forth. It's becomes a terrible way to drive. The reason we have 2 eyes is to be able to judge these things and it works fine if you aren't driving distracted.

Technology Connections on YT has. Awhile rant about this. https://youtu.be/U0YW7x9U5TQ?si=SZaEzNCDKoLXhx83

Because there are laws that specify when the brake light has to come on, and it isn't when the car shows down (slightly). You could be starting to go up hill, or a list of other reasons. The point of brake lights isn't too signify the car slowing, but that the driver intends to slow down. Which is also why it doesn't come on if you're motor breaking" (is that the right term?).

This obviously varies wildly depending on where you are in the world. I'm also sure there are some places where it would be allowed.

Because the brake light indicates braking, and is connected to the brake? This is already a perfect solution.

An accelerometer is a terrible idea to replace this. You would have to cover the car with sensors and tune them so that accelerating uphill doesn't trigger the brake light, and that braking downhill will successfully trigger the brake light.

Standardised is a funny word, a car manufacturer doesn't standardise. Laws and 3rd parties like ANCAP do.

When they need to do it to sell it with certain safety requirements, they will.

However, even if those happen, and car makers today start building them with that, it'll take a decade or longer before you'll start seeing them in majority on the road. So even if you lobby for it, expect time since I'd say less than half of all people buy new cars, so it's not until the second hand market sees it will it be commonplace.

Right now the second hand market is starting to see things like collision avoidance systems and they will often flash brake lights when emergency braking on behalf of the driver.

A related tangent is now that there are so many distracted drivers, engine braking in a standard can become hazardous. I often will tap my foot on the brake so the people behind will register that my speed is decreasing.

Ok i'll bite. Because why? How can you decelrate quickly enough to need to notify the driver behind you without braking?

That's a fairly complicated system to replace what is just an ultra simple switch at the pedal. The latter is even pretty likely to last the life of the car.

Because your life isn't worth the extra dollar to them.

There is a Technology Connections video about this xD:

https://www.youtube.com/watch?v=U0YW7x9U5TQ

I personally think cars should have two brake light switches. one for when you're pressing the pedal at all, and one for when you're slamming on the pedal.

that way the people behind you know if you're just slowing down a little or actually braking.

I would like if cars would somehow indicate how strong they are braking. Like a meter filling, the light starting to blink after a certain threshold and blinking faster etc.

One foot EV driving does turn on the brake lights when it exceeds a certain deceleration amount.

But most EVs default to slowly charging the car and slowing it in a similar way to ICE compression braking (which uses 0 fuel in fuel injected cars BTW).

Anyway regardless of how the vehicle is slowing down, the NHTSA allows for the brake lights to be activated by other devices that slow the car (not just the pedal), and the UN requires brake lights be applied if the vehicle deceleration exceeds

https://unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/R13hr2e.pdf

This is probably country/region specific but my car (Tesla) illuminates the brake lights when it detects a certain level of deceleration. Also my work vehicles (Volvo V90 CrossCountry and XC60) do this. Finland/Sweden in my case. My car also flash the hazards when it detects hard braking and I've seen quite many euro cars do this. I agree that this should be standard.

I feel like there must be a Technology Connections video about this.

That's how the car knows to deploy the safety systems including the seatbelt and airbags

I've driven rentals that put the brake lights on if you did not have a foot on the gas, and only lit a 3rd brake light when actually pressing the brake. Dunno why it isn't more common tho.

I always wanted a similar system to what you see in racing video games, when they display input controls. A red and green bar on the rear of the vehicle which shows accelerator pedal position, and a red bar which, in real life would have to show deceleration, as a percentage of theoretical maximum, rather than pedal position, as in the games.